1. Field of the Invention
The present invention relates to a television broadcast receiver for receiving television broadcast signals transmitted from multiple directions.
2. Description of the Related Art
In the North American Continent where ATSC (Advanced Television Systems Committee) digital television is broadcast, big cities spread across the plains. Accordingly, digital television broadcast signals, which are broadcast in big cities or their suburbs, can be received in other cities or intermediate areas between the cities. In addition, NTSC (National Television System Committee) analog television continues to be broadcast. From the viewpoint of each television user or viewer, television broadcast signals come from various directions. Thus, it is necessary for the television user to adjust the direction of an antenna in the direction of a broadcast tower transmitting a television broadcast signal of a television program which the user wishes to watch.
For this reason, multi-directional antennas such as a so-called smart antenna are put to practical use. The EIA (Electronic Industries Association)-909 standard provides a smart antenna having sixteen equiangular receiving directions in 360 degrees. Multi-directional antennas which are actually commercialized have various types such as one that changes the receiving direction by rotating the antenna using a motor, and one that has multiple antennas and selects an active antenna direction by turning on and off electronic switches (the antenna themselves do not rotate).
Some of television broadcast receivers each connected to such multi-directional antenna are each set to be able to adjust the receiving direction of the multi-directional antenna, and have an omni-directional scan function to automatically select the receiving direction of the multi-directional antenna in which a television broadcast signal of a channel selected by a television user can be best received (such receiving direction being hereafter referred to simply as “best receiving direction”). Receiving conditions of each of the above television broadcast receivers to receive television broadcast signals (terrestrial broadcasts) are considered to vary with time zone due to causes or influences of, for example, traffic amount, usage state of amateur radio, broadcast of another channel in an adjacent frequency band, and so on. However, conventional television broadcast receivers cannot properly adapt to the variations in time of the receiving conditions of the terrestrial broadcasts due to the above causes.